3d Tunnel Representation

1. A method performed in a processing unit, for generating a 3-dimensional representation of a tunnel, the method comprising the steps of: providing road network data including a plurality of road segments, at least one road segment being a tunnel road segment, including the information that the at least one road segment is a road segment located in a tunnel; identifying the tunnel segment in the road network, providing a geographical elevation map including elevation data of the geographical region in which the tunnel road segment is located; providing predefined patterns representing predefined parts of a 3-dimensional tunnel body; generating the 3-dimensional representation of the tunnel based on the tunnel road segment, the elevation map and the predefined patterns; and storing the 3-dimensional representation of the tunnel in connection with the road network as a 3-dimensional object which is located at the geographical position of the tunnel road segment, wherein the predefined patterns contain a left tunnel wall and a right tunnel wall, the 3-dimensional representation of the tunnel being generated using the tunnel road segment, the left tunnel wall and the right tunnel wall.

2. The method of claim 1 , wherein each tunnel wall contains, at its upper end, a curved surface, the curved surfaces of the left and right tunnel wall building a tunnel ceiling.

3. The method of claim 1 , wherein the predefined patterns contain an entrance and/or exit portal of the tunnel, the 3-dimensional representation of the tunnel being generated using the entrance and/or exit portal.

4. The method of claim 1 , wherein the 3-dimensional representation is generated by generating a 3-dimensional tunnel body including the tunnel road segment and the right and left tunnel walls, the tunnel body being embedded in the elevation map below a surface of the Earth.

5. The method of claim 4 , wherein the 3-dimensional tunnel body is generated in such a way that a tunnel ceiling is omitted from the 3-dimensional body, the left and right tunnel side walls extending from the tunnel road segment to the surface of the Earth.

6. The method of claim 4 , wherein the 3-dimensional tunnel body comprises a tunnel ceiling.

7. The method of claim 4 , wherein the position of the tunnel body below the surface of the Earth is determined by elevation data of a tunnel entrance and of a tunnel exit.

8. The method of claim 1 , further comprising the step of identifying the right and left tunnel wall for each driving direction in the tunnel and storing the identified left and right tunnel walls for each driving direction in the 3-dimensional representation of the tunnel.

9. A system configured to generate a 3-dimensional representation of a tunnel, the system comprising: a database containing road network data including a plurality of road segments, at least one road segment being a tunnel road segment including the information that the at least one road segment is a road segment located in a tunnel, the database furthermore containing an elevation map including elevation data of the geographical region in which the tunnel road segment is located, the database containing predefined patterns representing predefined parts of a 3-dimensional tunnel body; and a data processing unit configured to identify the tunnel road segment in the road network and configured to generate the 3-dimensional representation of the tunnel based on the tunnel road segment, the elevation map, and the predefined patterns, and configured to store the 3-dimensional representation of the tunnel in the database in connection with the road network as a 3-dimensional object which is located at the geographical position of the tunnel road segment, wherein the predefined patterns contain a tunnel wall, the data processing unit being configured to generate the 3-dimensional representation of the tunnel being generated using the tunnel road segment, the tunnel wall and the tunnel wall.

10. The system of claim 9 , wherein the data processing unit generates the 3-dimensional representation of the tunnel by generating a 3-dimensional tunnel body including the tunnel road segment and the tunnel walls, the tunnel body being embedded in the elevation map below a surface of the Earth.

11. The system of claim 10 , wherein the data processing unit generates the 3-dimensional body in such a way that a tunnel ceiling is omitted from the 3-dimensional body, the side walls extending from the tunnel road segment to the surface of the Earth.

12. The system of claim 10 , wherein the data processing unit embeds the tunnel body below the surface of the Earth in such a way that the position of the tunnel body image below the surface of the Earth image is determined by elevation data of a tunnel entrance and of a tunnel exit.

13. The system of claim 9 , wherein the data processing unit is configured to identify a right and left tunnel wall for each driving direction in the tunnel and configured to store the identified left and right tunnel walls for each driving direction in the 3-dimensional representation of the tunnel.

14. A method performed in a processing unit, for displaying a 3-dimensional route guidance information to a user of a navigation system, the method comprising the steps of: determining a route along which the user is moving; identifying a road segment as a tunnel road segment, wherein a road segment is a tunnel road segment when it includes the information that the road segment is located in a tunnel; generating the 3-dimensional representation of the tunnel, the 3-dimensional representation of the tunnel being generated based on the tunnel road segment, a geographical elevation map including elevation data of the geographical region in which the tunnel road segment is located, and predefined patterns representing predefined parts of a 3-dimensional tunnel body; and displaying a 3-dimensional route guidance information including a 3-dimensional representation of at least a section of the route and including the 3-dimensional representation of the tunnel, wherein the predefined patterns contain a tunnel wall and a tunnel wall, the 3-dimensional representation of the tunnel being generated using the tunnel road segment and the tunnel wall.

15. The method of claim 14 , wherein the 3-dimensional representation of the tunnel is generated by retrieving from a database the 3-dimensional representation of the tunnel as a 3-dimensional object stored in the database.

16. The method of claim 14 , wherein the 3-dimensional representation of the tunnel is only shown in the 3-dimensional route guidance information when a geographical region displayed as 3-dimensional route guidance information is smaller than a predefined threshold region.

17. A navigation system configured to display 3-dimensional route guidance recommendations to a user, the system comprising: a route guiding module configured to determine a route along which the user is moving and configured to identify a road segment as a tunnel road segment, wherein a road segment is a tunnel road segment when it includes the information that the road segment is located in a tunnel; an image viewer configured to generate the 3-dimensional representation of the tunnel, the 3-dimensional representation of the tunnel being generated based on the tunnel road segment, the elevation map, and predefined patterns representing predefined parts of a 3-dimensional tunnel body; and a display configured to display the 3-dimensional route guidance information including a 3-dimensional representation of at least a section of the route and including the 3-dimensional representation of the tunnel, wherein the predefined patterns contain a tunnel wall, the data processing unit being configured to generate the 3-dimensional representation of the tunnel being generated using the tunnel road segment, the tunnel wall and the tunnel wall.